In recent years, portable devices that are provided with display devices and use a limited electric power source like a battery, such as a smart phone, a mobile phone, and a portable television, have been developed, and display devices mainly used indoors, such as a TV and a monitor, have grown in size. Accordingly, many attempts have been made in order that electric power consumption is reduced in such display devices.
For example, according to a conventional technique, a data signal line drive circuit of a liquid crystal display device is configured such that 0V (GND) is supplied as a low power supply voltage, Vdd is supplied as high power supply voltage, and an amplifier circuit 100 whose input and output ranges are each from 0V to Vdd is provided for each data signal line S(m) (see (a) of FIG. 7).
In a case where the liquid crystal display device carries out reverse polarity driving such as dot inversion driving, line inversion driving, or frame inversion driving, the amplifier circuit 100 in the data signal line drive circuit is supplied with data signals of positive polarity and negative polarity. Thus, the amplifier circuit 100 needs to have a high withstand voltage, whereby the amplifier circuit 100 has a problem of electric power consumption.
In order to deal with this, the data signal line drive circuit may be configured such that, as the amplifier circuit, a positive polarity amplifier circuit 15 and a negative polarity amplifier circuit 16 are provided for each data signal line S(m) (see (b) of FIG. 7).
In the configuration of (b) of FIG. 7, the positive polarity amplifier circuit 15 is supplied with Vdd1 having a positive value, as the high power supply voltage, and is supplied with 0V (GND) as the low power supply voltage. Thus, the positive polarity amplifier circuit 15 has an output range of 0V (GND) to Vdd1.
On the other hand, the negative polarity amplifier circuit 16 is supplied with 0V (GND) as the high power supply voltage, and is supplied with Vdd2 having a negative value, as the low power supply voltage. Thus, the negative polarity amplifier circuit 16 has an output range of Vdd2 to 0V (GND).
Further, in the configuration of (b) of FIG. 7, an absolute value of a difference between Vdd1 and Vdd2 is set to be equal to an absolute value of a difference between Vdd and GND so that the output range becomes equal to that of the amplifier circuit 100 shown in (a) of FIG. 7. As a result, each of the positive polarity amplifier circuit 15 and the negative polarity amplifier circuit 16 has a considerably lower withstand voltage than that of the amplifier circuit 100 shown in (a) of FIG. 7.
Therefore, with an amplifier circuit configuration as those shown in (b) of FIG. 7, it is possible to provide a liquid crystal display device which consumes less electric power.